In drying a moving web of material, such as paper, film or other sheet material, it is often desirable to contactlessly support the web during the drying operation in order to avoid damage to the web itself or to any ink or coating on the web surface. A conventional arrangement for contactlessly supporting and drying a moving web includes upper and lower sets of air bars extending along a substantially horizontal stretch of the web. Heated air issuing from the air bars floatingly supports the web and expedites web drying. The air bar array is typically inside a dryer housing which can be maintained at a slightly sub-atmospheric pressure by an exhaust blower that draws off the volatiles emanating from the web as a result of the drying of the ink thereon, for example.
When floating light weight webs under medium to high tensions, machine direction corrugations often form in the web which can not be removed with prior art dryer nozzle arrangements. In addition, these hard-to-float light weight webs tend to have ink build up and marking problems when conventional nozzle arrangements are employed.
It therefore would be desirable to provide a flotation dryer having a nozzle arrangement that provides excellent web flotation, excellent drying and heat transfer performance, minimal or no web flutter, and minimal or no corrugation formation even in light weight webs.